Herschel Mission.

As we can see on this graphics, our eyes can only detect a very tiny part of the electromagnetic spectrum, called visible light. This means that there is a great deal happening around us that we cannot detect without instruments. Electromagnetic radiations from space are unable to reach the surface of the Earth except at a very few wavelengths, such as the visible spectrum, radio frequencies, and some ultraviolet wavelengths. space agencies, like ESA, have to get their various observatories above Earth's atmosphere to observe the universe according to the specific science objectives. Herschel and Planck will be the only space observatories to cover a spectral range from the far infrared to sub-millimetre. (Photo by API/Gamma-Rapho via Getty Images)